Thundering noise coming from hot taps,bath,sink taps...

remove the aerator from the end of the faucet where the water comes out and check there is no blockage or unwanted material. do this to both outlets. with the aerator removed open both taps and let the water run until all the air has come out. replace aerators if you wish.

You need to have the flow switch looked at. The low flow of the water to the lavs and the kitchen sink, they all have as small demand next to t bath or shower,
Tom

You will have to turn off your water mains and strip your mixer tap. It is possible that the seal (if it is an older tap with a rubber seal) has become stuck or the threaded part that turns it has gone faulty. If it is a modern tap with ceramic seals, check the operation of the mechanism and see why the ceramic seal is not being opened.

Confirm that the shut-off valve under the sink is open all the way. If it is, then close it and remove the cold water tap. If this is a single handle tap you will of course have to turn off the hot water shut off under the sink too.
With the tap removed and a bucket and towel handy, open the cold water shutoff just a little bit. If water comes rushing out, the problem is obviously with the tap. You may be able to clean or repair it, or you may have to replace it.

you may just have to replace the hot/cold stem

possible that the pipe's are not,secured properly in wall. and you did not say what kind of faucet you have, but if it has washer's,the screw's that hold them, may be loose.

Was the tap shut-off very tight and the tap is turning but the main shaft may not be turning. Check the hot tap mechanism and compare it to the cold tap.

You need to replace stem/cartridge assembly depends on the brand if it is a stem or a cartridge

Hmmm, Thunder flies usually are found on plants and vegetables, how did they get in your computer?

Regardless, they shouldn't stay alive in there too long, as they don't have any food feed off. Normally, I'd say don't worry about it and just let them die, but you may need to go in there and clean them out manually so they don't spread around your house too much.

can you check some other source of hot water? if the pressure there is ok?..if it is, then the problem is on the new tap that you fitted.